Permanent magnet hub motor hybrid magnetic pole built-in external rotor motor

Abstract

A hybrid magnetic pole built-in external rotor motor of a permanent magnet hub motor relates to the technical field of motors, the motor comprises an inner stator and an outer rotor, and a plurality of permanent magnet units are built in the outer rotor; the permanent magnet motor is characterized in that the permanent magnet units are divided into a group A and a group B, the two groups of permanent magnet units are alternately arranged around a rotating shaft of the outer rotor, the group A of permanent magnet units are arc-shaped magnetic steel symmetrically arranged relative to the d axis, and the group B of permanent magnet units are V-shaped magnetic steel symmetrically arranged relative to the d axis. The motor provided by the invention is good in flux weakening speed expansion capability.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to the technology of a permanent magnet hub motor with a hybrid magnetic pole internal outer rotor motor. Background Art

[0002] The air gap diameter of the outer rotor motor is larger than that of the inner rotor. It has high power factor, high efficiency, high output torque and moment of inertia, and is suitable for applications in low speed, high torque and direct drive. However, the cogging torque of the permanent magnet hub motor will produce speed and torque fluctuations, causing technical problems such as motor noise, vibration and deterioration of operation.

[0003] like Figure 2 As shown, the existing outer rotor motors are all surface mounted permanent magnet synchronous motors (SPMSM), which are mainly composed of an inner stator 72 and an annular outer rotor 71. The inner stator is located in the annular hole of the outer rotor, and the inner stator and the outer rotor are clearance-matched. The inner annular surface of the outer rotor 71 is evenly distributed with surface-mounted tile-shaped magnets 73 protruding radially inward. This surface mounted outer rotor permanent magnet synchronous motor has a permanent magnet with a magnetic permeability close to that of air, uniform air gaps between the cross and direct axes, and equal inductances between the cross and direct axes (Ld=Lq). It belongs to a hidden pole magnetic circuit and does not generate magnetic resistance torque. In addition, due to the large equivalent air gap, it is difficult to solve the problem of weak magnetic speed expansion. A large direct axis current must be passed through the stator winding to achieve the purpose of weak magnetic speed expansion. This method will reduce torque, increase stator loss, reduce drive system efficiency, and may cause the risk of irreversible demagnetization of permanent magnets. Poor weak magnetic speed expansion capability is the fundamental reason that hinders the development of SPMSM. Summary of the invention

[0004] In view of the defects existing in the above-mentioned prior art, the technical problem to be solved by the present invention is to provide a permanent magnet hub motor with a hybrid magnetic pole internal outer rotor that can reduce motor noise and torque fluctuation.

[0005] In order to solve the above technical problems, the present invention provides a permanent magnet hub motor with a hybrid magnetic pole internal outer rotor, comprising an inner stator and an outer rotor, wherein a plurality of permanent magnet units are built in the outer rotor; the characteristics are: The permanent magnet units are divided into group A and group B. The two groups of permanent magnet units are alternately arranged around the rotating shaft of the outer rotor. The permanent magnet units of group A are arc-shaped magnetic steels arranged symmetrically relative to the d axis, and the permanent magnet units of group B are V-shaped magnetic steels arranged symmetrically relative to the d axis.

[0006] Furthermore, both ends of the arc-shaped magnetic steel and the V-shaped magnetic steel are provided with air permanent magnet grooves.

[0007] Furthermore, the coercive force of the V-shaped magnetic steel is higher than the coercive force of the arc-shaped magnetic steel.

[0008] Furthermore, each stator tooth end surface of the inner stator is provided with a semicircular groove.

[0009] The permanent magnet hub motor provided by the present invention has a hybrid magnetic pole internal outer rotor motor, and the outer rotor adopts a salient pole structure. Arc-shaped magnetic steel and V-shaped magnetic steel are built into the outer rotor, so that the cross-axis inductance is greater than the direct-axis inductance, and it has a salient pole effect, so that the motor superimposes a reluctance torque on the basis of the permanent magnet torque. The existence of the reluctance torque is conducive to weak magnetic speed expansion, and it has the characteristics of good weak magnetic speed expansion capability, can improve the starting characteristics, overload capacity and power density of the motor, expand the constant power range operation, and obtain better weak magnetic speed expansion capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 1 is a schematic radial cross-sectional view of a permanent magnet hub motor with a hybrid magnetic pole internal outer rotor motor according to an embodiment of the present invention; Figure 2 Schematic diagram of radial cross section of the stator and rotor of an existing surface mounted outer rotor permanent magnet synchronous motor. DETAILED DESCRIPTION

[0011] The following is a further detailed description of an embodiment of the present invention in conjunction with the accompanying drawings, but this embodiment is not intended to limit the present invention. All similar structures and similar variations of the present invention should be included in the protection scope of the present invention. The commas in the present invention all represent the relationship of and.

[0012] like Figure 1-2 As shown, a permanent magnet hub motor hybrid magnetic pole internal outer rotor motor provided in an embodiment of the present invention comprises an inner stator 1 and an outer rotor 2, wherein the outer rotor 2 has a plurality of permanent magnet units built therein; The permanent magnet units are divided into group A and group B. The two groups of permanent magnet units are alternately arranged around the rotating shaft of the outer rotor 2. The permanent magnet units of group A are arc-shaped magnetic steels 21 arranged symmetrically relative to the d axis, and the permanent magnet units of group B are V-shaped magnetic steels 22 arranged symmetrically relative to the d axis. Both ends of the arc-shaped magnetic steel 21 and the V-shaped magnetic steel 22 are provided with air permanent magnet grooves; The coercive force of the V-shaped magnetic steel 22 is higher than the coercive force of the arc-shaped magnetic steel 21; Each stator tooth end surface of the inner stator 1 is provided with a semicircular groove 12 .

[0013] The motor using the permanent magnet outer rotor of this embodiment is compared with the existing surface-mounted permanent magnet hub motor using the same specification. The parameters of the existing motor with an internal double-layer U-shaped permanent magnet rotor are: rated power of 3KW, rated current of 19.5A, efficiency of 91.5%, rated speed of 800r / min, maximum speed of 2000r / min, rated torque of 35.8Nm, and maximum torque of 78Nm; Compared with the existing outer rotor surface-mounted permanent magnet hub motor of the same specification, the motor using the permanent magnet outer rotor of the embodiment of the present invention has an efficiency increased from 91.5% to 94.8%, a cogging torque reduced from 1.75 Nm to 0.78 Nm, a cogging torque fluctuation reduced from 4.9% to 2.17%, and a constant power speed regulation range increased from 800-2000 r / min to 800-2800 r / min.

[0014] It can be seen that the embodiments of the present invention improve the air gap magnetic flux density waveform and reduce motor noise and torque fluctuation.

Claims

1. A permanent magnet hub motor with a hybrid magnetic pole internal outer rotor, comprising an inner stator and an outer rotor, wherein the outer rotor has a plurality of permanent magnet units built therein; characterized in that: The permanent magnet units are divided into group A and group B. The two groups of permanent magnet units are alternately arranged around the rotating shaft of the outer rotor. The permanent magnet units of group A are arc-shaped magnetic steels arranged symmetrically relative to the d axis, and the permanent magnet units of group B are V-shaped magnetic steels arranged symmetrically relative to the d axis.

2. The permanent magnet hub motor hybrid magnetic pole internal outer rotor motor according to claim 1, characterized in that: Both ends of the arc-shaped magnetic steel and the V-shaped magnetic steel are provided with air permanent magnet grooves.

3. The permanent magnet hub motor hybrid magnetic pole internal outer rotor motor according to claim 1, characterized in that: The coercive force of the V-shaped magnetic steel is higher than the coercive force of the arc-shaped magnetic steel.

4. The permanent magnet hub motor hybrid magnetic pole internal outer rotor motor according to claim 1, characterized in that: Each stator tooth end surface of the inner stator is provided with a semicircular groove.

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